VAZ-2107. Fan switch: installation, repair, replacement

Most owners of VAZ-2107 cars faced the problem of engine overheating due to the late inclusion of the radiator fan. Such a malfunction poses a serious threat not only to the cooling system, but to the entire power unit. Increasing the coolant temperature to critical values is able to disable the head gaskets of the cylinder block, the valve cover, and cause jamming of the moving parts of the motor.

Most often the radiator fan does not work because of problems with the sensor of its inclusion. This can be both a banal absence of contact on the connectors, and the failure of the device as a whole. In this article, we'll talk about what measures can be taken if the VAZ-2107 sensor on the fan switch has lost its efficiency, and also consider the process of its verification and replacement.

Signs of engine overheating and precautions

If you find yourself at the wheel of a car that the pointer on the instrument indicating the temperature of the coolant has shifted to the red sector and continues to deflect towards the increase, it will be better to stop at the roadside and immediately turn off the engine. If this is not done, antifreeze or antifreeze will simply boil and try to break out, violating the tightness of the system. Continue movement in this situation is quite dangerous. Having stopped, it is necessary to check up working capacity of all elements of system of cooling and to establish the reason of an overheat. Further, if possible, it must be eliminated. And if this is not possible, tow the vehicle to the nearest service station.

What's wrong with the fan?

Suspected of overheating a faulty cooling fan, first check its operability. It is not difficult to do this. Disconnect an electric socket from the electric motor, and lead to its contacts electricity from the accumulator. Do not mix the polarity! If the fan does not work with direct connection, the cause must be searched in the electric drive. If the electric motor has earned, the problem, most likely, lies in the elements, ensuring its inclusion. This can be a fuse, relay, wiring and sensor.

Further verification

Further testing should be carried out according to the "from simple to complex" scheme. It is almost impossible to diagnose wiring without the appropriate tools and skills. The situation with the relay is the same. Check it yourself is unlikely to work, especially in the field. The only thing that can be done is to pull out a similar device from an adjacent socket or another car and insert it into the corresponding connector. Earned - the reason is set, the fan does not work - go ahead.

With the fuse test, there will be no problem. Find the desired insert in the assembly block, check it with a conventional tester or a homemade probe made of two wires and a lamp, and the result is obvious. If necessary, change the fuse and continue driving. But if this time you and I were mistaken, the problem should be looked for in the fan switch.

Features of the cooling system in different modifications

Before you begin to diagnose the sensor, you need to find it. The fact is that in carburetor "sevens" and a car with an adjustable fuel injection, it is in different places. Moreover, for injection machines VAZ-2107, there is no sensor for turning on the fan as such. Its functions are performed by the DTT (the coolant temperature sensor). Let us consider in more detail the arrangement of these devices in carburetor and injector "sevens".

Where is the fan switch?

For all obsolete modifications of the "classics" the sensor is located on the cooling radiator casing. To be precise, the lower right. From the outside it looks like a brass nut on the "30" with two contacts withdrawn. Raise the hood, look at the back of the radiator - you will definitely see it. The principle of the sensor is very simple. The thermoelement reacts to the temperature rise, closes the contact, and the fan is energized. For vehicles with controlled fuel injection, the fan is activated by the command of the electronic unit based on the data received from the sensor. In other words, the ECU itself controls all processes. But where is the sensor for turning on the fan at the injector "sevens"? As already mentioned, they do not have such a device at all. Do not look for it on a radiator or anywhere else! But pay attention to the thermostat. A coolant temperature sensor is mounted on its housing. It then transmits to the electronic control unit all the necessary information about the coolant temperature.

Checking the sensor

Now let's talk about how to test the fan switch (VAZ-2107). And start with the carburetor engine. Here everything is very simple. All you need to do is disconnect the wires from the sensor. To do this, remove the electrical connector from its terminals. To determine if the device is OK, turn on the ignition and close the contacts on the connector. If everything is in the sensor, the fan will turn on.

It can also happen that the fan switch does not respond correctly to the temperature. In other words, the mechanism of closing contacts works, but at a greater value. Thus, for VAZ-2107 carburetor machines, the fan switch must close the circuit when the coolant reaches a temperature of 92 degrees, and open at 87 ° C.

For engines with controlled fuel injection, the verification process is slightly different. Since the injector auto VAZ-2107 sensor does not include a fan, you need to check the temperature controller. But first, you should inspect the presence of voltage on the connectors of the connector. Take the tester and turn it on in the voltmeter mode. Minus the wire of the device close to the "mass", and connect the positive to the terminal "A" on the connector. Turn the ignition on. The tester should show a voltage of at least 12V. If its value is reduced, the problem should be sought in the control unit. But if the voltage is OK, unscrew the temperature controller from the nozzle for further testing.

Checking the sensor is to measure its electrical resistance at different temperatures. Put the tester into ohmmeter mode and measure the resistance on its contacts. It is noteworthy that it grows and falls inversely proportional to the temperature of the cooling liquid (20 ºС - 3,5 kΩ, 40 ºС - 1,5 kΩ, 80 ºС - 340 Ohm, 90 ºС - 250 Ohm). During the resistance measurement, the controller can be heated by placing it in a hot water tank. The temperature of the fan switch (VAZ-2107, injector) for different firmware versions of the computer can be 92-95 ° C. Its resistance is close to zero.

It should be noted that the sensors for switching on the fan and the coolant temperature are not subject to repair. Therefore, if they are found to have the slightest malfunction, they must be replaced. Consider the replacement process for each of the engines separately.

Process of replacement of the gauge on the carburettor engine

Here the process may seem more complicated. After all, given that the sensor is located at the bottom, you have to drain the coolant. And for this you need to look for an observation pit, remove engine protection, etc. But you can not do this. It's enough just to quickly wrap the new sensor in place of the old one. Naturally, a little cooling liquid will pour out, but its amount will be limited to 20-30 ml. In addition, under the place of connection, you can always substitute a properly cut plastic bottle.

So, prepare a new sensor and a wrench for "30". Disconnect the wires from the device. Carefully turn off the sensor with a wrench. Continue twisting it by hand, pressing it against the radiator housing. When the sensor comes off the thread, the hole can be clamped with a finger, and the other hand begins to screw in the new element. Do not manage to lose the O-ring, which is worn on the threaded part of the device. That, in fact, is the whole process. It remains to connect the wires to it, run the power unit and check whether everything works.

Replacement of the fan switch: VAZ-2107 (injector)

In the injector engine, there is no need to drain the coolant to replace the sensor. It is located high enough, so its outflow will be minimal. For replacement, a new temperature sensor and a key for "19" are required. First, we disconnect the connector, then unscrew the old controller and screw into its place a known good. Connect the power and start the engine. If done correctly, the fan is guaranteed to work.

Some useful tips

Before switching off the power supply of the sensors, especially on the "seven" with the injector motors, it is recommended to remove the minus terminal from the battery. When choosing a fan switch or coolant temperature, it is better to give preference to branded factory products. After replacement, do not forget to check the tightness of the threaded connection. If necessary, use a heat-resistant automotive sealant.